558. What will be the total current in figure «B» of the illustrated circuit with the switch closed if the applied voltage is 24 volts and the resistance of R is 3 ohms, R is 4 ohms, and R is 5 ohms, respectively

The total current is 2 amps. With the switch closed, the three resistors are in series, resulting in a total resistance of 12 ohms. Applying Ohm's law (I = E/R), the current is calculated as 24 volts divided by 12 ohms, yielding 2 amps.